Molded heat extractor connection



May 9, 1933. w. M. BAILEY 1,907,475

AMOLDED HEAT EXTRACTOR CONNECTION Filed May 2l, 1950 o o o /o Z0 vwembozPatented May 9, 1933 UNITED STATES PATENT OFFICE WILLIAM M. BAILEY, OFLYNN, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO GENERAL ELECTRICCOMPANY, A CBPORATION OF NEW YORK MOLDED HEAT EXTRACTOE CUNNECTIONApplication filed Hay 2, 31930. Serial No. 454,338.

This invention relates to condensers which are adapted to carrysubstantial current values and has for its object to lessen thetemperature increase of the condenser with a given value of current, byincreasing the electrical and thermal conductivity between the stack andan outer metal wall.

When aluminum is used as the material ot the casing or clamping abutmentand as a heat dissipator eXteriorly exposed to atmosphere, in additionto being an electrical conductor it has been discovered that theresistance and temperature increase of the device under load can belowered by the provision of some suitable means for avoiding reliancefor conductivity on the thin oxide film which seems to form on analuminum surface without being noticeable to the eye.

According to this invention an improved connection is made to analuminum heatdissipating wall by casting a copper strip into the walland having an end portion of the strip projecting flexibly therefrom torconnection to the stack.

Referring to the drawing Fig. 1 is a longitudinal section, through oneembodiment to this invention.

Fig. 2 is a bottom plan view of the device shown in Fig. 1 with thebottom plate removed and some of the wax broken away to reveal thestack.

This invention is illustrated as applied to a well known type ofhigh-frequency (radio) condenser having the casing 10 preferably ofaluminum in which is placed the mica foil stack 11 clamped between theadjustable end clamping plates 12 and 13 and provided with a highpotential terminal ifi leading to a midpoint of stack 11. As iscustomary a corona shield 15 is provided around the high potential leadand where such terminal 1d extends thru the casing it is provided with abushing shaped as illustrated which comprises a pyreX or borosilicateglass inverted bowl 16, secured to the casing by cement 17 as shown.Terminal 1d entends thru the smaller of the two oppositecasing-openings. 'llhis condenser body 11 is passed int-o the hollow,bon-like casing by way oit the larger and bottom opening. Within thecasing is thick wide Flexible strips 23, 24, and spread the usualreadily fusible wax embedment 18 cast in place around body 11 in thecasing by pouring when molten through the open bottom in the invertedcondition of the casing, Fig. 2; and after the embedment 18 has cooledand soldiied a bottom plate 19, Fig. 1, is secured in position. Thecasing is provided with the customary supporting lugs 20.

lln order to provide a connection of higher thermal and electricalconductivity between the stack or body ends and the casing on oppositesides, a Wide, thick flexible copper strip 21 is cast in place insidethe wall of the aluminum casing, with an end portion 22 of the stripprojecting flexibly from the casing .wall near the bottom casing openingbelow the body-clamp 13. Condenser body 11 in entering the casing,passes by flexible projecting strip-portion 23, and is clamped in placebetween 13-13. A thick, wide flexible copper lead 23 then is soldered at24 to the projecting end 220i strip 21 and soldered to the portion oi"the armature foils which project in a bunch from the condenser stack orbody. rlhe thermal and electrical connection ot this nature is the sameon the opposite sides of the casing' and ends oit the stack. Preferablythe conductive strips 21 and 23 are each otsuftlcient size so that theirelectrical and thermal conductivity is more than the electrical andthermal conductivity ot the foils in the stack. llt has been 'found thatnotwithstanding the high melting point U of the aluminum of the casing10, the integrity of the 'flexible portion 22 projecting from the casingwall after the casting ot the wall about the other end 21 of the strip,is preserved without injury to the continuity c with the aluminum casingwall, of the tier'.- ible projecting portion 22 of the strip, so that inetlect said portion 22 becomes an integral portion ot the casing wallaording perfect thermal and electrical connection between the strip andthe casing, so that all the heat developed inside the condenser body andconducted outside ot it by the projecting oilsbunch is conducted to thecasing by the thru the casing walls where it is dissipated into theatmosphere.

Among the advantages of this invention may be mentioned the lowertemperature increase with a given load and wave length than washeretofore possible. The soldered connections provide durable and highlyconductive connections. From Fig. 2 it will be seen that the thickconducting strips 23 are of substantial width in order to obtainsubstantial thermal conductivity. The nature of the wide, thick copperstrips 22, 23 is such that their free ends can be united thermally andelectrically at 24; and the other end of strip 23 can be unitedsimilarly to the condenser foil-bunch without injury to the foils. Theflexibility of the strips 23, 24 permits their manipulation for suchuniting by desired heat treatment. Furthermore, the nature of strip 22is such that one portion of its length can be cast and thereforeembedded in the casing wall without affecting its nonembedded portion orthe joint between said embedded and non-embedded length-portions. Asshown in Fig. 1, a very substantial portion of strip 21 is embedded incasing-wall 10, but that is not necessary because the effect ofembedding even a shorter portion of strip 21 in the casing-wall is toincorporate a portion of the strip as an integral portion of the wall sothat full thermal conductivity is established with the wall for theentire cross-sectional area of the strip, so that in effect theprojecting portion 22 of the strip is a projectin portion of thealuminum casing itself save or the desirable condition that projectingportion 22 is flexible for convenience of manipulation during heattreatment in uniting it with similar strip 23. This constructionprovides as effective a path of thermal and electrical conductivitybetween the condenser body and the heat-dissipating metal casing aswould be provided by a theoretic casting of the condenser foil-bunch inthe casing-wall which is apparently impossible for various obviousreasons. In order to make sure that the finished product has the desiredthermal conductivity, a heat run may be made with a thermometer placedadjacent the lower soldered joint 24 so as to see if the temperatureincrease under given load measures up to the expected results, i. e.have been lessened to the desired extent. As is shown, as to the wideembedded strip 21 in the wall 10, both are in a plane parallel to theplane of the foils in condenser-body 11, so that the width of Widestrips 22, 23 extending from Wall 10 extends generally parallel to thewide end of the foil-bunch projecting from the lower side of the end Vofcondenser-body 11, and consequently the wide end of strip 23 can bemoved up alongside the Wide end of' the foil-bunch so that the widths ofboth lie alongside, after body 11 has been clamped in place between thetwo opposite casingwalls, into position for soldering said wide endstogether face to face to provide the good thermal connection betweenbody 11 and strip 23.

What I claim is:

1. A condenser structure including a, condenser body having widearmature foils projecting from it in a bunch as a thermal and electrlcalterminal of the body; a hollow boxlike metallic casing inside of whichsaid condenser body is located, said casing having its exterior surfaceexposed to atmosphere as a heat-dissipating surface of large area, thewall of the casing lyin in a plane paralleling the width of said widefoil-bunch; and a Wide, thick, flexible metallic strip having a portionof one end embedded in said wall of the casing, the width of saidembedded portion of the strip extending parallel with said Wall, and theother portion of the length of the embedded strip extending flexiblyinto the interior of the casing w erein the width of said free end ofthe strip extends alongside the width of said foil-bunch projecting fromthe condenser body.

2. A hollow box-like metallic enclosing casing, terminal and externalheat-dissipator for an electrostatic condenser, and a wide, thick butflexible metallic strip for connecting said heat-dissipating casin tothe enclosed condenser, said Casin aving comparatively thin walls, andormed with a large opening for entrance of the condenser body; saidstrip having a portion of one end embedded in a wall of the metalliccasing, the width of said embedded portion of the strip extendingparallel with the casing wall in which it is embedded, and the otherportion of the embedded strip extending flexibly into the interior ofthe casing from a portion of said wall near said opening in the casing.

3. A condenser structure including a condenser bodyhaving wide armaturefoils projecting from it in a bunch as a thermal and electrical terminalof the body; a second terminal from the condenser-body of substantiallygreater length than the first; a. hollow box-like metallic casing insideof which said condenser body is located, said casing having its exteriorsurface exposed to atmosphere as a heat-dissipating surface of largearea; said casing being formed with two opposite openings respectivelylarge and small; said second body-terminal projecting out thru saidsmall casing-opening, and the other opening being sufficiently large forpassage of the condenser body into the interior of the casing; and saidfirst body-terminal lying inside the casing; one wall of the casingextending parallel with the width of said foil-bunch body-terminal; anda wide, thick, flexible metallic strip having a portion of one wide endembedded in said wall of the casing, the width of said embedded portionofthe strip extending parallel with said wall, and the other portion ofthe length of the embedded strip extending iiexibly from a portion ofsaid wall near said large opening in the casing to the interior of thecasing wherein the width of said free end of the strip extends parallelto the width of said foil-bunch projecting from the condenser body.

4. A condenser structure including a condenser body having armaturefoils projecting from it in a bunch as a thermal. and electricalterminal of the body; a hollow boxlike metallic casing inside which saidcon denser body is disposed, said casing having its exterior surfaceexposed to atmosphere as a heat-dissipating surface of large area, saidbody terminal lying within said casing; and a metallic leadsubstantially thicker than the individual armature foils of the terminalbunch but flexible, one portion of the length of said lead beingembedded in the metal of said casing and the rest of its lengthextending from said wall into the interior of the casing and iiexibletoward the armature foils.

5. A condenser structure including a condenser body having armaturefoils projecting from it in two foil-bunches as thermal and electricalterminals of the electrical ends of the body at the same potential; ahollow box-like metallic casing inside which said condenser body isdisposed, said casing having its exterior surface exposed to atmosphereas a heat-dissipating surface of large area, said body-terminals lyinginside the casing; said casing being formed with respectively large andsmall openings in opposite walls; a mid-point terminal lead extendingfrom the enclosed condenser body out of the casing thru said smallopening; the large casingopening being suiiciently large for passage ofthe condenser body into the interior of the casing; and two widemetallic strips thicker than the individual armature foils of thecondenser body, portions of the ends of said strips being embedded inopposite walls of the metallic casing, and the other ends of said stripsprojecting from said walls along lines near said larger casing-openingand extending flexibly into the interior of the casing wherein they aremovable toward said foilterminals of the condenser body.

In testimony whereof I hereunto ailix my signature.

WILLIAM 'M. BAILEY.

